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I have heard of AFB's and WCFB's but a AVS???? Well i happen to have one, and will be in the process of putting a kit in it, here shortly. Does anybody know ANYTHING about them (cfm, application, etc..). All i know this one is from a 66-67 chevy 327, but thats about it. It looks the same as an AFB. Are they rare? Heres the number off of it if that helps, front pad 4028S and below that L5. Thanks for all your help.
 

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This carb was used on the '66 Chevelles with the 327 275hp engine along with other applications. AVS stands for Air Valve Secondary. It works on the same principal as the quadrajet. A couple of friends had Chevelles with this setup back in '66 and they seemed to run just fine and gave good gas mileage to boot.
 

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Man sorry I cant remember anything about the AVS, however, I used to have a dual-quad setup with two AFB's and since I didnt know much about them I bought a book (available at Borders books) called Carter Carburetors that will tell you everything about them... might want to check into that?? good luck

-mike
 

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Thanks for the replies. So do the secondaries open up like on a Q-jet then? Will say a strip kit for the 9000 series AFB's work for this or not?. Does anybody know the CFM on them? Will this carb work well next summer when i put in a bigger cam/ and gears or should i go with a holley dble pumper?(All out racing action next summer). Mike how much did that book cost? (approx). Keith if AVS stands for air valve secondary, then what does AFB stand for? Thanks agian for all your help, as i am just a poor college student trying to keep my chevelle going, I really appreciate it!
 

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The AVS (Air Valve Secondary) Carter is exactly the same as any AFB (Aluminum Four Barrel) on the primary side.

The secondaries are the main difference. Instead of booster venturis in the mainstream of the secondaries for the fuel to be pulled from, there are two fuel dump tubes, one for each secondary main jet, and the air break plates that are normally underneath the booster venturis on the AFB are removed and one large air break plate is mounted above the fuel dump tubes and venturi area. When the vacuum pull from the secondary butterflys makes the area under the butterflys get vacuum buildup, fuel is pulled through the secondary jets, tubes and then opens the air break plate. the plate is adjustable for tension and opening vacuum by changing the tension on the plate return spring.

If the secondarys bog, readjust the spring tension by loostening the set screw and turning the spring stop bolt to a different setting, then lock the set screw down, and try it. The secondary air valve must close all the way for proper secondary operation. A little movement on the set screw and spring does a lot to the plate opening.

There aren't any needles in the secondary system of the AVS, just the plate tension and jets to make the system work. When the secondaries are adjusted correctly, the transition from primary to secondary barrels should be smooth and without surge.

I think the aftermarket should have built this carb instead of just remarketing the AFB. Carter and Edelbrock dropped the ball, the AVS is clearly the better design.
 
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